There's something in the air: Allergies and global warming

The forecast calls for earlier and longer hay fever seasons.

Can global warming change your life? If you are an allergy sufferer, it probably already has.

Climate change may already be making life worse for you and the roughly 30 million to 40 million allergy sufferers nationwide, according to a study released earlier this year. Rising carbon dioxide levels are driving the growth of the plants that make us sneeze, wheeze and sniffle each spring, summer and fall.

We humans consider carbon dioxide to be an inconvenient truth about our addiction to fossil fuels, but to plants, carbon dioxide is breakfast, lunch and dinner. Via photosynthesis, plants use carbon dioxide and sunlight to create the energy they need to grow.

Plants not only are growing more quickly and larger but they are also making more pollen than they used to. One study suggests that the pollen may be more allergenic. In addition to this carbon overdrive, warmer temperatures are triggering plants to release pollen earlier and survive longer, extending the overall allergy season. A study in Switzerland published in fall 2008 found that birch trees are, on average, releasing pollen 15 days earlier than they used to.